Researchers from the University of Illinois say supervolcanoes may erupt when cracks form in the roof of chambers holding their molten rock – exactly what can happen during an earthquake.

"Typically, when we think about how a volcanic eruption is triggered, we are taught that the pressure in the magma chamber increases until it causes an explosion and the volcano erupts,” says volcanologist Patricia Gregg, the study’s lead author.

"It's very likely that supereruptions must be triggered by an external mechanism and not an internal mechanism, which makes them very different from the typical, smaller volcanoes that we monitor."

One of the reasons we understand so little about what triggers a supervolcano eruption is that no supervolcano has been active since humanity began keeping detailed records. Equally, we don’t have a full understanding of the consequences of an eruption.

"A typical volcano, when it erupts, can have lasting impacts across the globe," Gregg said. "We've seen that in Iceland when we've had large ash eruptions that have completely disrupted air traffic across Europe. A supereruption takes that to the nth degree."

It’s estimated that an eruption of the Yellowstone supervolcano could be 1,000 times more powerful than the Mount St Helen eruption of 1980, releasing a mixture of magma, vapour, rocks and gases out of the ground.

In the aftermath, a layer of molten ash one foot deep could spread for more than 1,500 kilometres, killing around 90,000 people.

Yellowstone’s supervolcano has had three major eruptions in history. The supervolcano last erupted 174,000 years ago and last flowed with lava around 70,000 years ago.

The first eruption 640,000 years ago created the famous Yellowstone Caldera, a cauldron-like volcanic crater that measures 48 kilometres wide and 72 kilometres long.